# Difference or Gap of days between two given dates using C#

In this tutorial, you will be learning how to find the difference or gap between two dates in C#.

The user will enter two dates in the form of DD\MM\YYYY. The total number(gap or difference) of days between two date is an output.

#### Design:

There are many approaches to solve this problem:

- The first approach is to find the number of days from the date d1 to date d2.
- The second approach is to find the number of days(nd1) before the date d1 i.e., from 00/00/0000 and number of days(nd2) before the date d2. The difference between the two days(nd2-nd1) obtained is the actual gap between the two dates.

We will implement the second approach as it is straight forward and easy to understand.

#### Example:

Let the two dates be:

d1 = 2/2/2018

d2=1/2/2019

Count number of days before d1. Let this count be nd1. The leap year contains an extra day that has to be added to nd1.

nd1 = year*365+month[i]+dd+number of leap year.

where 1<=i<mon and month[] is array of no of days in each month

Therefore nd1=2018*365+(31)+2+number of leap years.

#### To calculate the number of leap years:

Count of **leap year** for a date ‘dd/mm/yyyy’ can be calculated using the following formula:

- Number of leap years = y/4 – y/100 + y/400 if m > 2
- Number of leap years= (y-1)/4 – (y-1)/100 + (y-1)/400 if m <= 2

(All above divisions must be done using integer arithmetic so that the remainder is ignored)

for date** 2/2/2018**, the number of leap year is:

Number of leap years=2017/4-2017/100+2017/400=**489 ** (using 2nd formula as m<=2)

Therefore, nd1=2018*365+(31)+2+489=**737092**

Similarly, find the number of days before date2, i.e nd2=**737456**

Therefore, the number of days between date1 and date2 is (nd2-nd1) **364 **days.

## Difference between two dates in C#

Below shows the program to find the number of days between two dates in C# using the above approach.

// C# program two find number of days between two given dates using System; class pgm { public class Date { public int day, mon, year; }; static void get_date(Date d) { Console.WriteLine("Enter day:"); d.day=int.Parse(Console.ReadLine()); Console.WriteLine("Enter month:"); d.mon=int.Parse(Console.ReadLine()); Console.WriteLine("Enter year:"); d.year=int.Parse(Console.ReadLine()); } static int []monthDays = {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31}; // This function counts number of // leap years before the given date static int countLeapYears(Date d) { int years = d.year; // Check if the current year // needs to be considered // for the count of leap years or not if (d.mon <= 2) { years--; } return years / 4 - years / 100 + years / 400; } // This function returns number // of days between two given dates static int getDifference(Date dt1, Date dt2) { // COUNT TOTAL NUMBER OF DAYS // BEFORE FIRST DATE 'dt1' // initialize count using years and day int nday1 = dt1.year * 365 + dt1.day; // Add days for months in given date for (int i = 0; i < dt1.mon- 1; i++) { nday1 += monthDays[i]; } // Since every leap year is of 366 days, // Add a day for every leap year nday1 += countLeapYears(dt1); // SIMILARLY, COUNT TOTAL // NUMBER OF DAYS BEFORE 'dt2' int nday2 = dt2.year * 365 + dt2.day; for (int i = 0; i < dt2.mon - 1; i++) { nday2 += monthDays[i]; } nday2 += countLeapYears(dt2); // return difference between two counts return (nday2 - nday1); } public static void Main(String[] args) { Date dt1 = new Date(); Date dt2 = new Date(); Console.WriteLine("Enter the date in the pattern i.e dd/mm/yy"); Console.WriteLine(" First Date :"); get_date(dt1); Console.WriteLine(" Second Date :"); get_date(dt2); Console.WriteLine("******First Date******"); Console.WriteLine(dt1.day+"\\"+dt1.mon+"\\"+dt1.year) ; Console.WriteLine("******Second Date*****"); Console.WriteLine(dt2.day+"\\"+dt2.mon+"\\"+dt2.year) ; Console.WriteLine("******Result*****"); Console.WriteLine("Difference between two dates is " + Math.Abs( getDifference(dt1, dt2))+" days"); } } // This code is contributed by DEVIPRASAD D MAHALE

#### Output:

Enter the date in the pattern i.e dd/mm/yyyy First Date Enter the date:2 Enter the month:2 Enter the date:2018 Second Date: Enter the date:1 Enter the month:2 Enter the date:2019 ********** First Date ********** Date is 2/2/2018 ********** Second Date ********** Date is 1/2/2019 ********** Result ********** Difference between two dates is 364 days.

Hope you have understood the above program to find the difference or gap between two given dates in C#.

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